Therapeutic cells, cells which may be introduced into a human for the treatment of disease, are being developed. Examples of therapeutic cells include pluripotent stem cells such as human embryonic stem cells (hESCs) which have the ability to differentiate into any of the three germ layers, giving rise to any adult cell type in the human body. This property of stem cells provides a potential for developing new treatments for a number of serious cell degenerative diseases, such as diabetes, spinal chord injury, heart diseases and the like. However, there remain obstacles in the development of such hESC-based treatments.
Obtaining and maintaining adequate numbers of therapeutic cells in cell and tissue culture and ensuring that these cells do not change in unwanted ways during cell culture are important in developing and controlling therapeutic cell cultures. For example, stem cell cultures, such as hESC cell cultures, are typically seeded with a small number of cells from a cell bank or stock and then amplified in the undifferentiated state until differentiation is desired for a given therapeutic application. To accomplish this, the hESC or their differentiated cells are typically cultured in the presence of surfaces or media containing animal-derived components, such as feeder layers, serum, or Matrigel™ available from BD Biosciences, Franklin Lakes N.J. These animal-derived additions to the culture environment may expose the cells to potentially harmful viruses or other infectious agents which could be transferred to patients or which could compromise general culture and maintenance of the hESCs. In addition, such biological products are vulnerable to batch variation, immune response and limited shelf-life.
Recently, synthetic surfaces that are free of animal-derived components have been shown to be successful in the culture of stem cells, such hESCs, in chemically defined medium, addressing many of the issues that result from culturing cells in the presence of animal-derived components. However, such synthetic surfaces have been made with high concentrations of recombinant polypeptides, which can be expensive to manufacture. In addition, these synthetic surfaces may provide surfaces from which cells cannot readily be removed, often requiring long incubation times with proteolytic enzymes such as trypsin combined with cell scraping.